Instrumental analytical packages with large number of elements
For geochemical exploration of the base metals, we recommend aqua regia digestion of the sample and multi-element analysis by ICP-OES (Method 511P). The package can be upgraded by additional ICP-OES-elements or ICP-MS- analysis to include larger set of elements and lower detection limits (Method 511PM).
Alternative package which includes elements Au and Pt, is method 515PM. This method employes also a larger subsample weight of 5g.
Although aqua regia is a powerful leaching agent, it still produces a partial dissolution for many elements. The dissolution of silicates and refractory minerals (e.g. baryte, chromite and other spinelles, zircon, cassiterite, tourmaline) varies depending on different factors. Most of the sulphide, carbonate and oxide minerals (ore forming minerals) are, however, dissolved. The data will also give information on alteration and weathering of rock and till samples.
Multi-acid near-total digestions and ICP-OES and ICP-MS –analysis (306P and 306PM or 307M) are also available for geochemical samples.
As geochemical methods have been optimised for analysis of large set of elements preferably with low detection limits, they have analytical limitations on very high concentrations. Thus the laboratory has defined upper concentration level for each element. When this concentration is exdeeded, a more suitable ore grade assay method should be used for checking the grades. The optional method for most elements is sodium peroxide fusion with ICP-OES finish (method 720P). Sample with high grades of Ag (>200ppm) , should be analysed by Fire Assay -method with gravimetric finish (method 704G) and high concentrations of sulphur (>5%) should be checked with combustion technique (method 810L).
The multi-element packages may have to be complemented with element-specific, individual method for elements or components which cannot be analysed by these analytical packages with compromised digestion/pretreatment and instrumental methods. These methods include high -grade sulphur-, carbon-, Hg-analyses, physical parametres like loss-on-igntion, specific gravity, saturation magnetisation (SATMAGAN) etc.
The analytical schema may require analyses of the elements in specified mineralogical phase e.g. Ni in sulphides and silicates, carbonate and non-carbonate carbon. For these analyses look Additional analyses.